Thermal powered hydronic chiller using low grade heat

ABSTRACT

This invention employs an arrangement of flat plate heat exchangers and a pump that function as a thermal powered hydronic ammonia absorption chiller. Chilling is achieved by bubbling ammonia gas through a liquid refrigerant causing a reduction of the partial pressure of the refrigerant and evaporation with the absorption of heat. The refrigerant and working fluids can be selected to have a broad range of operating pressures. If the refrigerant and working fluid are selected so that the atmospheric boiling point is the about the same as the highest operating ambient temperature, the chiller can operate with low, or even no internal pressure. The low operating pressures allow the use of light weight materials, easy fabrication, low cost and safety. This chiller is especially suited for using solar heated water, cooling water from internal combustion engines or any source of hot water. The chiller is easily scalable to any size and will find wide application for comfort air conditioning or food storage.

CROSS REFERENCE TO RELATED APPLICATIONS

Not Applicable

FEDERALLY SPONSORED RESEARCH

Not Applicable.

SEQUENCE LISTING OR PROGRAM

Not applicable.

BACKGROUND

1. Field

This invention pertains to the field of refrigeration, specifically tothe utilization of low grade heat in the form of hot water by means offlat plate heat exchangers to power an absorption chiller that operatesat low internal pressure, is cheap to build and scalable.

2. Prior Art

My invention improves on concepts of prior art that were first publishedin the USA by Einstein and Szilard in U.S. Pat. No. 1,781,541. U.S. Pat.No. 1,781,541 disclosed a refrigeration cycle and an arrangement ofchambers and tube-in-shell heat exchangers wherein ammonia gas isbubbled through liquid butane to produce a refrigeration effect byevaporating butane. (FIG. 1) The ammonia gas is separated from thebutane vapor by absorbing the ammonia into water, to produce ammoniasolution and liquid butane which easily separate by gravity due to theirmutual insolubility and different densities. The ammonia gas is thenregenerated by heating the ammonia solution to complete the cycle.

Surprisingly, there have been very few references to U.S. Pat. No.1,781,541 in the patent literature in the 79 years since it was firstpublished. A search of the patents referring to U.S. Pat. No. 1,781,541returned 6 references, none of which pertain directly to advancing themechanics which utilize the physical chemistry concepts introduced byU.S. Pat. No. 1,781,541.

Though the physical chemistry of U.S. Pat. No. 1,781,541 is wonderfullyclever, the apparatus proposed for carrying out the chemistry isprimitive. The prior art relies on a bubble pump to circulate theworking fluids. The bubble pump is not scalable due to the well knownsquare-cube relationship.

If the bubble bump in U.S. Pat. No. 1,781,541 is heated very slowly, thesolution in the bubble tube will become depleted of ammonia and becomelocked. Subsequent application of high heat to the bubble tube will notun-lock the device. Slow heating is precisely the situation encounteredwith the rising sun each morning. Thus the device presented in U.S. Pat.No. 1,781,541 is probably not reliable for solar applications.

U.S. Pat. No. 1,781,541 does not give any hints for calculating therequired capacity for any of the 5 heat exchangers in the originaldisclosure. The lack of full disclosure in U.S. Pat. No. 1,781,541 makesit impossible for one skilled in the art to construct a practicalworking machine. As will be demonstrated in this disclosure, theefficiency of the chilling is dependent on the correct sizing of theheat exchangers.

In U.S. Pat. No. 1,781,541, there is no provision for recovering heatfrom the ammonia gas leaving the generator before it enters theevaporator. Residual water vapor in the ammonia gas will condense in theevaporator reducing the overall efficiency of the system.

U.S. Pat. No. 1,781,541 specifies the use of butane as a refrigerant.Butane has the disadvantage of having a vapor pressure that is higherthan atmospheric pressure at normal ambient temperatures. Butane's highvapor pressure requires an apparatus that can hold high pressure. If aleak were to develop in a device using butane, a noxious, flammablemixture of ammonia and butane could be aspirated into the surroundingenvironment with dangerous consequences.

The present invention addresses the deficiencies in U.S. Pat. No.1,781,541 by applying modern advancements in flat plate heat exchangerdesign, most importantly to the advancement of brazed heat exchangers.Other areas of advancement include the development of seal-lessmagnetically driven pumps, and brazing metallurgy that did not exist in1930 when U.S. Pat. No. 1,781,541 was granted.

Because of the deficiencies in the original patent disclosure, theEinstein Refrigeration Cycle has remained a dormant technology for 79years. The present invention addresses the deficiencies to produce achiller that can operate on low grade heat from solar collectors orwaste heat from the cooling water of internal combustion engines.

Calculation methods disclosed herein have lead this inventor to thesurprising conclusions that the refrigerant, specific ammoniaconcentrations, and heat exchanger capacities can be selected so thatthe system can operated at atmospheric internal pressure. Thissurprising conclusion was not reported by Einstein and Szilard and isessential for the Einstein Refrigeration Cycle to become practical,safe, working invention for the benefit of mankind.

DRAWINGS Figures

FIG. 1 The prior art disclosed in U.S. Pat. No. 1,781,541.

FIG. 2. Example of one kind of plate heat exchanger.

FIG. 3. The Thermal Powered Hydronic Chiller.

FIG. 4 a. The Linear Aspirator. The gas mixture (27) is mixed with theweak solution and distributed among the plates of the absorber (13) inthe linear aspirator (32).

FIG. 4 b. The Linear Bubbler. The ammonia gas (26) is introduced intothe evaporator (11) below the level of the refrigerant (25) anddistributed among the plates of the evaporator.

FIG. 5 Solar powered air conditioner or refrigerator configured from theThermal Powered Hydronic Chiller. The Chiller of FIG. 2 is powered by ahydronic solar collector (33) and cooled by water from a cooling tower(34).

FIG. 6 Waste heat powered air conditioner or refrigerator configuredfrom the Thermal Powered Hydronic Chiller. The waste heat from thecooling water of an internal combustion engine is used to power theChiller. Cooling is provided by fluid circulating through a fan coil(35).

DRAWINGS---Reference Numerals. 11 EVAPORATOR 12 COLD ECONOMIZER 13ABSORBER 14 HOT ECONOMIZER 15 GENERATOR 16 GAS COOLER 17 GAS CHILLER 18SEPERATOR 19 STRONG SOLUTION PUMP 20 CHILLED FLUID PUMP 21 HOT FLUIDPUMP 22 COOLING FLUID PUMP 23 AMMONIA STRONG SOLUTION 24 AMMONIA WEAKSOLUTION 25 REFRIDGERANT LIQUID 26 GAS, AMMONIA GAS 27 GAS MIXTURE,AMMONIA GAS + REGRIDGERANT GAS. 28 CHILLED FLUID 29 HOT FLUID 30 COOLINGFLUID 31 LINEAR BUBBLER 32 LINEAR ASPIRATOR 33 HYDRONIC SOLAR COLLECTOR34 COOLING TOWER 35 FAN COIL 36 INTERNAL COMBUSTION ENGINE.

Table 1 Calculation of Heat Exchanger Size and Relative CoolingCapacity. Table 2. Comparison of Refrigerant Performance. SUMMARY OFINVENTION

This invention employs an arrangement of flat plate heat exchangers anda pump that function as a thermal powered hydronic ammonia absorptionchiller. Chilling is achieved by bubbling ammonia gas through a liquidrefrigerant causing a reduction of the partial pressure of therefrigerant and evaporation with the absorption of heat. The refrigerantand working fluids can be selected to have a broad range of operatingpressures. If the refrigerant and working fluid are selected so that theatmospheric boiling point is the about the same as the highest operatingambient temperature, the chiller can operate with low, or even nointernal pressure. The low operating pressures allow the use of lightweight materials, easy fabrication, low cost and safety. This chiller isespecially suited for using solar heated water, cooling water frominternal combustion engines or any source of hot water. The chiller iseasily scalable to any size and will find wide application for comfortair conditioning and food preservation.

DETAILED DESCRIPTION

FIG. 3 shows the arrangement and interconnections of flat plate heatexchangers and a pump comprising the physical design of the chiller ofthe invention. Each heat exchanger is given a name according to itsfunction. Any source of hot water and cooling water can be used to powerthe chiller.

The arrangement of the heat exchangers and the fluid levels must followa few rules for stable operation:

-   -   As the strong solution (23) is heated, and ammonia gas (16) is        released, the flow of the liquid must be ascending so that the        gas will follow the path of the liquid and the now weal solution        (24) will be expelled from the top of the generator (15). The        gas cooler must be above the gas chiller and hot economizer must        be above the gas cooler and the generator must be above the hot        economizer.    -   Once the gas is separated from the weak solution it must always        be descending. The gas cooler must be above the gas chiller        (17), and the chiller. The descending path is necessary so that        water vapor can condense as strong solution and flow out of the        evaporator and into the separator and not condense in the        evaporator (11).    -   The levels of strong solution is selected so that when the        system is running, there is no accumulated fluid inside the        absorber (13). Fluid is continuously cascading down the plates        of the absorber (13) and running out the bottom under the force        of gravity.    -   The position of the evaporator (11) and the refrigerant level is        adjusted so that gas separates from liquid in the top of the        evaporator without bubbling over into the gas chiller (17) or        the cold economizer (12).    -   The separator and strong solution pump are in the lowest        position.

Description of Heat Exchangers.

The general characteristics of flat plate heat exchangers that makesthem useful in this invention are compact size, low internal volume, canbe easily scaled to any size and are cheap to manufacture. Scalaradjustments covering orders of magnitude can be made by changing thesize of the plates. Smaller adjustments can me made by changing thenumber of plates.

Many patents are on record that describe refinements to the developmentof flat plate heat exchangers. U.S. Pat. Nos. 4,872,578, 3,240,268, and4,987,955 describe suitable designs, but the present invention is notlimited to these designs.

The plates within the heat exchangers are corrugated. The corrugationsare arranged so that when the plates are stacked, a series of wavychannels are created between the plates promoting turbulence. Turbulencewithin a heat exchanger is desirable as it disrupts the boundary layersbetween the solid plate and the flowing liquid promoting efficient heatexchange.

Flat plates heat exchangers can be brazed, gasketed or assembled usingadhesives or sealants. Brazed heat exchangers have advantages in thepresent invention as they are resistant to the possibility of leakage ofammonia and refrigerant. Gaskets and sealants must be compatible withammonia solution, and the refrigerant while operating at 80° C. and haveno leakage. Copper containing heat exchangers are not suitable due tothe aggressive action of ammonia toward copper.

Aluminums high thermal conductivity and low cost and passivity towardammonia make it a desirable material for constructing heat exchangersfor this invention. Aluminum brazing plate is especially a useful.Brazing plate consists of two alloys arranged in three layers. A highmelting alloy core is clad on both sides with a low melting alloy skin.The brazing plate is formed into corrugated heat exchanger plates,stacked into a heat exchanger and fused in a furnace at temperaturebetween the melting points of the two alloys.

Stainless steel brazed with nickel foil might be considered when thesource of hot water or the cooling water is corrosive to aluminum. Theheat exchangers might also be assembled out of a plastic material thatis resistant to the refrigerant and ammonia such as PVC.

Description of Gas-Liquid Mixing Devices.

At the top of the absorber and the bottom of the evaporator, gas must bebrought into intimate contact with liquid. Efficient operation of thechiller depends on mixing the gas and liquid in a way that evenlydistributes the mixture across all of the plates of the heat exchanger.

FIG. 4 a. shows the arrangement within the absorber (13) of a linearaspirator. The weak solution and the ammonia gas are rising verticallyin separate tubes. The two separate tubes make a 90 degree bend and arecombined into one tube which and then enters the absorber (13),extending horizontally across the breadth of the absorber. Along thelength of the tube is a row of holes located along the side of the tube.As liquid and gas enter the tube, the liquid will fill the bottom halfof the tube up to the row of holes and the gas will fill the top half ofthe tube. As the liquid and gas escape through the holes the velocity ofthe gas will be around 280 times the velocity of the liquid. As the gasand liquid escape the holes moving at different velocities, a shearingforce will be applied to the liquid causing atomization and a dramaticincrease in the surface area of the liquid promoting rapid absorption ofthe ammonia gas with the associated increase in temperature due to theheat of absorption. As the atomized liquid encounters the plates of theheat exchanger, the liquid will cascade downward under the force ofgravity, transferring the heat to the cooling water and completing theabsorption of ammonia to regenerate strong solution. At the same timeliquid refrigerant is regenerated due to the insolubility of refrigerantin the strong solution.

The arrangement shown in FIG. 4 a is the simplest way to construct alinear aspirator, but that particular configuration must be installedprecisely in a, horizontal position. Another way to construct a linearaspirator that is not so sensitive to horizontal installation is toinsert a second tube with a row of holes that line up and are in closeproximity of the holes of the larger tube. As weak solution emerges fromthe holes of smaller tube, will be carried through the holes of thelarger tube by the higher velocity gas.

FIG. 4 b shows how ammonia gas is introduced into evaporator (11) bymeans of a tube with a row of small holes along its length so that thebubbles are distributed equally among the plates of the evaporator (11).As the gas rises through the evaporator, it encounters the corrugationsof the heat exchanger plates and is broken into small bubbles with highsurface area which promotes rapid evaporation of pentane into theammonia with the absorption of heat.

Description of the Pumps.

The pumps are very small in relation to the amount of low grade heatthat they utilize. There are 4 pumps in the system.

The motive force to circulate the fluids within the chiller is providedby the strong solution pump (9). When the chiller is operating, ammoniaweak solution (23) enters the top of the absorber (13) and cascades downthe plates, and runs out under the force of gravity. To maintain theabsorber in a state where the plates are continuously wet with fluid butnot filled with fluid, a pump must overcome a fluid head that is theheight of the absorber.

The pump must be absolutely leak proof, resistant to ammonia solution,resistant to refrigerant and able to withstand the maximum pressure thatthe system may encounter. The pump should also be very energy efficient.One suitable type of pump is the magnetically coupled centrifugal pump.

The pump can be surprisingly small. A centrifugal pump that deliversless than 5 l/min to a height of 300 mm and draws less than 20 watts ofelectricity can circulate fluid to utilize 5000 watts of hydronicthermal energy and produce 9,000 watts of cooling power. A pump so smallcan be economically powdered by solar voltaic cells.

The other pumps circulate fluids outside of the chiller and will likelybe located remotely with respect to the chiller.

The chilled fluid pump (20) circulates cold fluid, to a fan coil orsimilar device to absorb heat and produce the desired cooling effect.The chilled fluid should have some additive, such as ethylene glycol,added to prevent freezing within the evaporator. the chilled fluid pumpmust be compatible chilled fluid and withstand constant exposure tocold.

The cooling fluid pump (22) circulates fluid between the cooling sourceand absorber.

The hot fluid pump (21) circulates fluid from the heat source to thechiller.

Description of Ammonia Solutions.

When ammonia gas dissolves in water the water gets hot. The dissolvingreleases 7.29 kJ/mol, the heat of solution. The reaction is reversible.If a saturated solution of ammonia is heated by an external source ofthermal energy, it will release ammonia gas, consuming 7.29 kJ/mol ofheat plus the heat required to raise the temperature of the gas andremaining solution.

The boiling point of aqueous ammonia is linear with respect toconcentration over the range of 2% to 50%. The boiling point of a 23%solution is 42° C. and the boiling point of a 6% solution is 78° C.

If 100 g of a 23% solution of ammonia is heated to 78° C. at atmosphericpressure, it will release 17 grams of ammonia gas (1 mole) and will havea volume of 28.8 liters at 78° C., a 288 fold increase in volume.

The amount of heat required to release the 17 grams of ammonia (1 mol)from 100 ml of 23% solution will be the sum of three heats:

-   -   1. Q1=The heat required to heat 77 grams of water from 42° C. to        78° C.=11,587 J.    -   2. Q2=The heat required to heat 23 grams or ammonia gas from        42° C. to 78° C.=1,705 J.    -   3. Q3=The heat of solution of ammonia, for one mole of        ammonia.=7,729 J.

The actual work that we want done, the desorption of ammonia gas,requires 35% of the energy. The remaining 65% of the energy is used toheat the ammonia gas and the remaining ammonia solution.

The efficient recovery of thermal energy, through the use of flat plateheat exchangers, from the weak solution and ammonia gas is the centralfeature of this invention.

Description of Refrigerant.

One advantage of this invention is the possibility to build arefrigeration device that that operates at low internal pressure. Lowinternal pressures allow the heat exchangers to be made of thinmaterials which improves the heat transfer, lowers the cost ofmaterials. Lowering internal pressure will also increase the safety ofthe device. The internal pressure is set by the choice of refrigerantand the concentration of the ammonia solution.

N-pentane and cyclopentane are a good model compounds to demonstrate theproperties of the refrigerant because the thermal properties are wellunderstood, and widely published. N-pentane has a boiling point of 36°C. and cyclo pentane has a boiling point of 49° C. N-pentane can beblended with cyclo pentane to make a mixture that will not boil on a hotsummer day thus insuring that the system will not become pressurized.The properties of a few refrigerants are listed in Table 2.

Higher molecular weight refrigerants with a higher boiling point andlower vapor pressure would be desirable if the chiller were installed ata high elevation. If the chiller were installed in an automobile thatmight move from low elevations to high elevations, the designer wouldhave a choice as to whether to use higher molecular weight refrigerantsor build the device to hold the higher internal pressure that would beencountered at higher elevations. This invention disclosure is notlimited by the choice of refrigerant.

In practice, the refrigerant need not be a pure substance and can be amixture of paraffinic petroleum distillates. White gas, such as the fuelthat is commonly used in camping stoves and lanterns could be used as arefrigerant. One widely distributed brand of white gas, Colman® CampFuel has boiling point around 47° C. and a vapor pressure of 518 mm Hg @20° C. compared to n-pentane with a vapor pressure of 427 @20° C.

Example 1

The principles of operation will be illustrated by calculating therequired heat exchanger capacities and cooling power for 1 Watt of powerinput using n-pentane as a refrigerant. The calculations are shown in ain Table 1 in a spreadsheet format that is used by the widely availablecomputer program Microsoft Excel.

Design calculations assume that it is possible to exchange 90% of theheat difference between two fluids and that fluids will be brought towithin 2° C. of each other.

Table 1 is annotated with references to FIG. 3.

Lines 1 through 7 list the design parameters for the specificapplication of this invention.

Lines 8 through 24 list the physical properties of the fluids.

Lines 24 through 40 shows the calculations for the fluid flows.

Lines 42 through 52 show the calculations for the required heatexchanger capacities.

The cooling process begins with a continuous stream of ammonia gas (27)entering the evaporator (11) through the linear bubbler (31) to bubbleup through the n-pentane contained in the evaporator (11). Line 42 ofTable 1 predicts that 1.83 W of cooling power will be produced from eachwatt of power input at the generator.

The cold gas mixture (27) exiting the evaporator is split between thecold economizer (12) and the gas chiller (17) where it cools theincoming refrigerant and gas. The cold economizer will require a heattransfer capacity of 0.318 W and the gas chiller will require a capacityof 0.150 W . Lines 43 and 45.

The gas mixture then moves to the linear aspirator (32) which isinstalled into the top of the absorber (13).

On line 29 we calculated that 1 W of power input would desorb 0.00198g/s of ammonia gas would require 0.0138 g/s of strong solution heatedfrom 42° C. to 78° C. to reduce the concentration of ammonia from 23% to6%. Line 37. The strong solution pump (19) moves strong solution fromthe separator (18) to the gas cooler (16), where it absorb heat from theammonia gas (26) at a rate of 0.138 W to increase it's temperature by2.5° C. But more importantly, the process of removing water vapor fromthe ammonia gas is begun.

From the gas cooler (16), the strong solution moves to the hoteconomizer (14) where it absorbs recycled heat at a rate 1.73 W forevery new watt of power input to the system. The remarkable size of thehot economizer compared to the generator is one of the surprisingdiscoveries of this invention.

By the time the strong solution exits the hot economizer, it hasreleased most of its ammonia gas using only heat that has been recycledin the hot economizer and gas cooler. Now the solution moves in to thegenerator to absorb 1 W of external power. Weak solution (24) andammonia gas (26) exit the generator and are separated into differentstreams.

The ammonia gas (26) moves to the gas cooler (16) and then the gaschiller (17) to complete the gas cycle.

The weak solution (24) moves to the hot economizer (14) to preheat thestrong solution (23) and then to the linear aspirator (32) to mix withthe gas mixture (27) be injected into the absorber (13).

Overall, heat enters the chiller in two places: the generator (15) andthe evaporator (11). The only place that heat can leave the chiller isthrough the absorber (13). The absorber is sized to transfer thecombined the heat from the generator (15) and evaporator (11). Theabsorber (13) must transfer 2.83 W to the cooling water for every 1 W ofheat input to the generator (15). Line 47 With 2.83 W of heattransferred by the absorber (13) to cooling water at 40° C., the strongsolution (23) and refrigerant (25) will be returned to 42° C., thestarting temperature. The refrigerant (25) and strong solution (23)drain out to the absorber into the separator (18) and the cycle repeats.

More Examples

The spreadsheet used to calculate Table 1 was used to calculate theperformance of other refrigerants based on their physical properties.Though cyclopentane and neohexane are slightly less efficient thann-butane or n-pentane, they have the advantage of having vapor pressuresat 40° C. that are well below atmospheric pressure. A refrigerationsystem using cyclopentane or neohexane will not become pressurized at40° C. and will be safer. Butane will develop considerable pressureunder normal operating conditions and will require heavier materials toconstruct the heat exchangers. Off setting the added cost of materialsand complexity of construction is the slightly more efficient operation.This invention is not limited by the choice of refrigerant. Anyrefrigerant can be used.

CONCLUSIONS RAMIFICATIONS AND SCOPE

Accordingly, the reader will see that I have set forth an invention thatcan utilize low grade heat in the form of hot water to power a chillerthat is made up of an arrangement of flat plate heat exchangers and apump.

My invention provides a means to use water heated with solar energy toreplace electricity for comfort air conditioning. Summer cooling demandis the highest peak demand on the national electricity grid. Thewidespread adoption of this invention will reduce the consumption offossil fuels for electricity generation.

One obstacle to the widespread use of hydronic solar collectors is thatif they are sized to produce enough heat in the winter, they produce toomuch heat in the summer. My invention provides a useful application forhydronic solar collectors in the summer time. Once solar collectors areinstalled and paid for by the savings in electricity from summercooling, they are immediately available for collecting heat for winterheating. As a result, my invention will impact the burning of fossilfuel for heating and cooling year round.

Solar powered refrigeration using my invention provides a means topreserve food in remote areas that are not served by electricity. Thiswill allow food that is produced by small farmers and hunters in remoteareas to be accumulated until there is enough to transport to marketeconomically.

My invention provides a means to co-generate cooling power together withelectricity using an internal combustion engine. Electricity can begenerated using the mechanical energy of an engine running on naturalgas and cooling power can be generated using the thermal waste.

Automotive air conditioning using my invention will increase the gasmileage of cars by using waste thermal energy and eliminating the needfor mechanical energy for air conditioning.

While the above description contains many specifics, these should not beconstrued as limitations on the scope, but rather as an exemplificationof a few embodiments. Many other variations are possible.

TABLE 1 Calculation of relitive heat exchanger size and coolingcapacity. A B C D 1 Dimension Spread Sheet Formulas 2 System pressure.The system pressure is chosen by selecting the 873 mmHg refrigerant andstrong solution concentration. The system pressure will be the sum ofthe partial pressures at the cooling water temperature. 3 Input power.HE5 1 W 4 Temperature ° C. of heat source. 80 ° C. 5 Temperature ofcooling water. 40 ° C. 6 Target evaporator temperature. 5 ° C. 7Refrigerant. N-pentane 8 Molecular weight g/mol. 72.15 g/mol 9 Vaporpressure of pentane @ 40° C. 873 mmHg 10 Vapor pressure of pentane @ 5°C. 231 mmHg 11 Heat of vaporization @ 5° C. kJ/mol 26.75 kJ/mol 12Pentane liquid heat capacity kJ/mol 167.19 kJ/mol°K 13 Pentane gas heatcapacity 120.07 J/mol°K 14 Pentane gas heat capacity 1.66 J/g°K 15 WaterCp 4.18 J/g°K 16 Molecular weight of NH3 17.03 g/mol 17 Ammonia heat ofsolution, kJ/mol*-1 7.29 18 Heat capacity NH3 Cp (g) 35.06 J/mol°K 19Heat capacity NH3 Cp (g) 2.06 J/g°K =B18/B16 20 % concentration ofammonia having a boiling point of 42° C.* ″23% #N/A 21 Estimate the heatcapacity of 23% ammonia solution. 3.69 J/g°K =0.23 * B19 + 0.77 * B15 22% concentration of ammonia having a boiling point of 78° C.*  ″6% #N/A23 Estimate of heat capacity of 6% ammonia solution. 4.05 J/g°K =B19 *0.06 + B15 * 0.94 24 Heat capacity of pentane/NH3 gas mixture leavingevaporator. 1.82 J/g°K =B32 * B13/B8 + B33 * B18/B16 25 Q1, 10% of heatto bring 0.77 g water from 42° C. to 78° C. 11.6 J/g =0.1 * 0.77 * B15 *36 26 Q2, 10% of heat to bring 0.23 g ammonia from 42° C. to 78° C. 1.70J/g =0.1 * 0.23 * B19 * 36 27 Q3, Heat from 1 W input available tostrong solution to desorb ammonia. 0.85 W =0.17 * B28/(0.17 * B28 +B26 + B25) 28 Joules required to desorb from water one gram NH3. 428.07J/g =(B17 * 1000)/B16 29 Grams per second NH3 desorbed by 1 watt ofpower. 0.00198 g/s =B27 * B16/(B17 * 1000) 30 Mol fraction of pentane(g) in vapor over pentane liquid in evaporator. 0.265 =B10/B2 Calculatedby applying Daltons Law. 31 Mol fraction of NH3(g) in vapor over pentaneliquid in evaporator. 0.735 =1 − B30 32 Weight fraction of pentane(g) invapor over pentane liquid in evaporator. 0.604 =(B30 * B8)/((B30 * B8) +(B31 * B16)) 33 Weight fraction of NH3(g) in vapor over pentane liquidin evaporator. 0.396 =1 − B32 34 Heat absorbed by vaporizing refrigerantper g of NH3 to evaporator. 935.93 J/g =((B11 * 1000)/B8)/B33 35Refrigerant evaporated by 1 watt of power input. 0.00301 g/s =B36 − B2936 Flow of vapor from evaporator per W power input. 0.00499 g/s =B29/B3337 Strong solution required to release 23%--->6% NH3 gas per 1 W. 0.0138g/s =0.00234/((23 − 6)/100) 38 g/s weak solution flow. 0.0118 g/s =B37 −B29 39 Heat absorbed by vaporizing refrigerant per 1 watt of powerinput. 1.85 W =B34 * B29 40 Required cooling power for ammonia enteringevaporator. 7° C. →5° C. 0.00813 =2 * B29 * B19 41 Required coolingpower for pentane entering evaporator. 7° C. →5° C. 0.01000 W =2 * B35 *B14 42 Net cooling power from evaporator per 1 W power input.Preliminary. (1) 1.83 W =B39 − B41 − B40 43 Cooling power from gasentering cold economizer. 5° C.--> 40° C. (2) 0.318 W =B24 * B36 * 35 44Required cooling power for pentane in cold economizer. 42° C. →7° C.0.244 W =35 * B12 * B35/B8 45 Cooling power needed to cool NH3 (gas)44°C.-> 7° C. (7) 0.150 W =B29 * B19 * 37 46 Heat available from NH3 (gas)78° C.-->44° C. (8) 0.138 W =B29 * B19 * 34 47 The absorber transfersthe combined heat from the power input and the 2.83 W =B42 + 1evaporator to cooling water at 40° C. (3) 48 Temperature rise of strongsolution across (6) 2.45 =0.9 * B46/(B37 * B21) 49 Required capacity for(4) for strong solution flow. 44--->78° C. 1.73 W =B37 * B21 * 34 50Available heat for (4) from flow of weak solution 78--->44° C. 1.62 W=B38 * B23 * 34

TABLE 2 Comparison of refrigerant performance. n-pentane cyclopentaneneohexane n-butane Molecular weight g/mol. g/mol 72.15 70.01 86.2 58.1Vapor pressure of pentane @ 40° C. mmHg 873 551 548 3565.13 Vaporpressure of pentane @ 5° C. mmHg 231 134 138 1173.47 Heat ofvaporization @ 5° C. kJ/mol kJ/mol 26.75 27.3 27.93 22.3 liquid heatcapacity J/mol kJ/mol°K 167.19 159.5 191.5 132 gas heat capacity J/mol°K120.07 73.69 142.26 98 Net cooling power from evaporator per 1 W powerinput W/W 1.83 1.77 1.71 2.01

1. A thermal powered hydronic chiller comprising: a. generator (15)consisting of a flat plate heat exchanger in which ammonia gas (26) isgenerated by transferring the heat from a hot fluid to an ammonia strongsolution (23), b. a hot economizer (14) comprised of a flat plate heatexchanger, disposed at a level below said generator, in which the heatfrom the ammonia weak solution (24) exiting said generator istransferred to said strong solution (26), c. an evaporator (11)consisting of a flat plate heat exchanger, in which said gas (26) isbubbled through a refrigerant my means of d a linear bubbler (31)consisting of a horizontal tube with a plurality of holes along the topof its length causing said gas to be distributed among the many platesof said evaporator (11), causing said refrigerant (25) to evaporate atreduced temperature and transfer heat to a fluid to be chilled, e. acold economizer (12) consisting of a flat plate heat exchanger, in whichsaid refrigerant (25) entering said evaporator (11) transfers heat tothe cold gaseous mixture (27) of ammonia and refrigerant (25) exitingsaid evaporator (11), f. an absorber (13) consisting of a flat plateheat exchanger in which said weak solution (24) and said gaseous mixture(27) are mixed and introduced into the top of said absorber (13), bymeans of g. a linear aspirator (32) comprised of a horizontal tube witha plurality of holes along its length in which said gaseous mixture (27)and said strong solution (23) escape at different velocities causingintimate mixing and distribution among the plates of said absorber (13),transferring heat to a cooling fluid, causing said strong solution (23)and said refrigerant (25) to be regenerated as separate liquid phasesand drain out the bottom of said absorber (13) and into f. a separator(23) consisting of a container of sufficient horizontal area to causesaid refrigerant (25) and said ammonia strong solution (23) to separateinto two distinct phases, disposed at a level that is below theevaporator (11), so that only refrigerant (25) will flow to said coldeconomizer (12) and said strong solution (23) will flow to g. a pump(19) disposed at the bottom of the separator (18) so that it only drawsstrong solution (23) and discharges said strong solution to the inlet ofsaid hot economizer.
 2. The thermal powered hydronic chiller in claim 1in which a. a gas cooler (16) consisting of a flat plate heat exchangeris disposed below said hot economizer, receiving gas flowing in adownward direction and transfers heat from said gas to said strongsolution (23) prior to discharging of said strong solution to said hoteconomizer, b. a gas chiller (17) consisting of a flat plate heatexchanger disposed at a level below said gas cooler, receiving gas fromsaid gas cooler flowing in a downward direction, transferring heat to aportion of the cold said gaseous mixture from the evaporator, andcollecting condensed water vapors for discharge to said separator priorto discharging said gas to said evaporator.
 3. The thermal poweredhydronic chiller in claims 1 and 2 in which, said generator, hoteconomizer, gas cooler gas chiller cold economizer and evaporator areassembled as a contiguous series of heat exchangers in which thedischarge of one heat exchanger is mated directly to the inlet of thenext heat exchanger.
 4. The thermal powered hydronic chiller in claims1, 2 and 3 in which said hot fluid is an aqueous fluid supplied by asolar collector.
 5. The thermal powered hydronic chiller in claims 1, 2and 3 in which said hot fluid is the aqueous cooling fluid of aninternal combustion engine.
 6. The thermal powered hydronic chiller inclaims 1, 2 and 3 in which said hot fluid is the cooling fluid of anelectric motor.
 7. The thermal powered hydronic chiller in claims 1, 2and 3 in which said hot fluid is derived from water used to scrub flugas.
 8. The thermal powered hydronic chiller in claims 1, 2 and 3 inwhich said hot fluid is flu gas.
 9. The thermal powered hydronic chillerin claims 1, 2 and 3 in which said hot fluid is heated by the engineexhaust gas of an internal combustion engine.
 10. The thermal poweredhydronic chiller in claims 1, 2 and 3 in which said hot fluid isinternal combustion engine exhaust gas.